in the mock debates, senator rob portman is playing barack obama. >> i don't like him very much anymore. >> reporter: as for president obama, he took a break from practice yesterday to visit a campaign office and make a few calls to unsuspecting voters. >> andrea? hi. this is barack obama. how are you? that's right. >> reporter: it was just a brief break for the president, who, like romney, has been rehearsing for days. senator john kerry is playing romney in president obama's practice sessions. the president is out of practice. the last time he debated was four years ago. and, rob and paula, according to the latest abc news/"washington post" poll, 56% of americans expect president obama to win the debates. mitt romney told voters yesterday, the debates are about more than who comes out on top. they are a chance for a month-long conversation with the american people. >> managing expectations, as always. tahman bradley, live in washington for us. thanks, tahman. >>> and abc news coverage of the debate begins tomorrow night at 9:00 eastern, 6:00 pacific. keep right here on abc. >>> and th